[The role of the kidney and liver in the total metabolism of (125I) ortho-iodobenzoate in rats].

The contribution of the kidney and liver to the total metabolism of (125I)ortho-iodobenzoate (OIB) was studied in rats with the aim considering the suitability of the use of this radiopharmaceutical as a diagnostic agent of the conjugation function of the liver. For the analysis of OIB metabolism (formation of conjugates with glycine and glucuronic acid) in rats, the techniques of the perfused rat kidney "in situ" and the isolated perfused rat livers were used. A comparison of the relative representation of OIB metabolites in the urine of intact rats with the results obtained in the urine from the perfused kidney and the perfusion fluid from the isolated perfused liver gives evidence of preferential biotransformation of OIB in the kidney. As shown in a biodistributional study of OIB in rats, OIB concentration in the renal tissue and thus the supply for the metabolic processes in the kidney is higher by orders than it is in the liver tissue, which could explain the above-mentioned finding. Assuming that the biotransformational organ capacity for this drug in man is similar to that in the experimental rat, the use of OIB for quantification of the detoxicating function of the liver in man is debatable.